Conventionally widespread contact adhesives are of a solvent type comprising an organic solvent having uniformly dissolved therein 20 to 35% of solid matter, comprising natural rubber or a diene compound polymer such as a synthetic rubber and additives such as a tackifying resin, a plasticizer, and an antioxidant. However, adhesives of the solvent type are costly due to a use of large amounts of an organic solvent. Besides, the organic solvent must be evaporated, which involves deterioration of the working environment, danger of fire, and air pollution.
In order to provide an adhesive which is free from the above problems while exhibiting adhesion performance comparable to the conventional solvent type adhesives, a contact adhesive of a solventless type comprising a modified silicone polymer has been proposed as disclosed in JP-A-3-263478 (the term "JP-A" as used herein means an "unexamined published Japanese patent application").
However, the contact adhesive using a modified silicone polymer as disclosed in JP-A-3-263478 is disadvantageous in that it requires a long time for developing sufficient tackiness for making assembly possible (hereinafter referred to as a tack developing time) and that it has insufficient tack strength and poor workability due to its high viscosity.
An object of the present invention is to provide a curable composition which develops tackiness rapidly, retains the developed tackiness for a long time (the time during which the tackiness is exhibited will hereinafter be referred to as a tack range), exhibits sufficient tack strength, satisfactory initial and final adhesive strength, and is excellent in workability. In particular, the present invention is to provide a curable composition which develops sufficient tackiness rapidly and forms excellent cured products.